


Guinea Pig

by PinkPandorafrog



Series: Omega-for-hire [3]
Category: Marvel Cinematic Universe
Genre: Alpha/Beta/Omega Dynamics, Aromantic, F/M
Language: English
Status: Completed
Published: 2016-01-30
Updated: 2016-01-30
Packaged: 2018-05-17 04:00:48
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,527
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5853277
Author URL: https://archiveofourown.org/users/PinkPandorafrog/pseuds/PinkPandorafrog
Summary: <blockquote class="userstuff">
              <p>Darcy's a little surprised when Tony Stark contacts her, but he's a friend of a friend and all that. Turns out he's been working on a formula that would trigger a heat in a Beta or an Omega, he just needs her to test it out.</p>
            </blockquote>





	Guinea Pig

Darcy was more than a little surprised to hear from Tony Stark, mostly because everyone knew he was a Beta. But he was a friend of a friend and all that, so she agreed to meet him. Yet again her tiny balcony came in handy when fucking _Iron Man_ touched down out there. There was barely enough room for him to step out of the suit, but he did, and let himself into her tiny apartment.

She was sitting on the bed, more for lack of anywhere else to sit, and he came through and flopped down right next to her like it was no big deal. Sure, relaxing on a bed with Tony Stark was something that happened all the time. He propped himself up on his elbow and looked at her for a bit. “Hi.”

“Hi.” She looked down at him for a second. “I'm Darcy.”

He nodded. “I know. I am _so_ happy to meet you.” He watched her for a moment. “I have a proposition for you.”

Her eyebrows rose a little as she looked at him, and she kinda shrugged. “Okay...”

“I understand you have a certain job.” His expression wasn't judgmental, though, he looked like he was just looking for confirmation.

She shrugged. “I'm an Omega-for-hire if that's what you mean.”

“That is precisely what I mean. Me and my esteemed colleague, one Dr. Banner, have been working on a formula that would trigger a heat in an Omega or a Beta.” He looked a little pleased with himself about that.

Her eyebrows rose even more like they were trying to climb up her forehead. “That's interesting.” That would be very interesting. Being able to go into heat more often than once a month might boost her earning potential, but she was more interested in the other part of it. If a Beta could go into heat...

Jane was in a rather unusual relationship with an Alpha and another Beta. Between her and the other Beta they could mostly get their Alpha through his ruts, but it wasn't quite enough. Not quite. And he was the kind of guy who would just sort of suffer in the name of a committed relationship. Whatever, Darcy wasn't going to judge. But if one of them could experience a heat with him, that would probably help immensely.

“Wow. That sounds...” She grinned at him.

“Yeah. Exactly.” Tony nodded. “I mean, I've tested it. It works, at least on a Beta. I'm hoping, though, to get a friendly, helpful Omega to test it out and see if it actually reads like a heat and it's not just the Diet Coke of heats.”

She shook her head, her grin growing. “And you're hoping I'll volunteer to be a guinea pig?” Because why else would he be in her apartment?

“Yeah. Basically that's about the size of it. You were recommended on account of your fantastic secret-keeping abilities as well as being...” He trailed off for a second and waved one hand in a circle. “Thor has a lot of positive adjectives he used to describe you, I sort of tuned out after the first five minutes.” He looked up at her for a moment, eyes studying her face. “So? Are we feeling guinea piggish?”

She didn't even have to consider it. If this could help Jane... “I mean, yeah. I don't...” She thought for a second, then shook her head. “I don't really know anyone who's going into a rut at any point in the near future. Thor would probably know someone, though.” Being knotted by an Asgardian seemed to work out pretty well for her the last time. She'd definitely needed some recuperation time, some of her muscles were still a little twingy.

“I can take care of that as well, actually.” His eyes moved over her for a second. “I happen to know a guy.” And without giving her a chance to say anything else, he pulled his phone out of the pocket of his cargo pants and swiped at it a couple of times before holding it to his ear. “Yes, dear,” he agreed to whoever was on the other end, a bit of a smirk on his face. “I happen to be sitting, well, laying, in front of a _very_ sexy Omega right now. I'm assuming that you, of course, have postponed making arrangements for your rut out of some sort denial.” He fell silent for a second, and the smirk widened into a broad grin. “You remember telling me that if I got that formula worked out you'd help test it?” Another pause. “Uh, no, I'm pretty sure you owe me at this point. Besides which, I'd be saving you from your usual last minute arrangements with the Air Force's matchmaking service.” Another pause. “Right, like you've ever had any problem finding me before. Okay, see you soon.”

He pulled the phone away from his ear practically bounced up off her bed and to his feet. He took a look around her apartment before peering outside at the balcony. “Well, this isn't really going to work very well. How does Thor fit in here, anyway?”

Darcy shook her head. “With great difficult.”

“I bet. Come on, we're going out for...” He glanced at his phone before putting it back in his pocket. “Lunch. Dinner. Something.”

Feeling a little bit bemused, Darcy got to her feet as well and found her shoes, slipping them on before following him out the front door. Apparently he was walking?

They ended up at the little cafe she'd met Phil at for her first job a couple of months ago. This time, though, she was not the only one to get coffee. Tony got himself some food, a sandwich and some kind of gooey dessert bar that looked really, really good. She just had a coffee, she was actually feeling a little bit nervous.

Okay, and that was definitely War Machine making his way towards them. He was wearing an actual Air Force uniform, looked pretty good to be honest. He settled himself down at the table and gave Tony a look before he turned his attention to Darcy. He offered her his hand. “I'm Jim.”

“Darcy. Nice to meet you?” It came out a little more question-y than she'd wanted, but he gave her a smile.

“Tony has a habit of blowing through like a hurricane and taking everything else along with him.”

That certainly seemed to be true. Tony swallowed his bite of sandwich and looked between them. “Everyone acquainted? Perfect. So?” He turned his attention to the other man at the table, an expectant expression on his face.

“Slow down a little. How is this even supposed to work?” Jim asked, folding his arms on the table in front of him.

Tony stared at him for a second. It was a good question, Darcy had been wanting to ask too. “Well... I give our lovely Omega volunteer a shot of the formula. It's based off the pheromones an Alpha in rut gives off, only concentrated, with a few minor tweaks. You go into heat within an hour, and I think you're both familiar with what happens after that.” He glanced between them, giving Darcy a wink.

Jim's eyebrow raised a little. “What if it doesn't work?”

“Then you go back to the Air Force and do one of your last minute deals like you're used to. No big thing.”

Jim shook his head. “I was wondering more about Darcy.” His attention shifted over to her, and she could see the concern in his dark eyes.

Tony shrugged. “Then Darcy goes home until Bruce and I tweak the formula. Or...” He turned his attention to her. “You come with me so you're on hand to test it. Whichever.” He shrugged. “It works, Rhodey. It works. I've tested it, I just need to know if it reads like an actual heat. I have no perspective for that sort of thing.”

Jim sighed. He was silent for a moment like he was considering it. “You don't have to do this, you know,” he told Darcy.

“I know. But I have a feeling it'll be a huge help for someone I love very much, so...” It was her turn to shrug. “I'm in. I'm just...” Her attention shifted back to Tony. “I'm a little concerned about how quickly it's supposed to kick in and the timing of it all.”

“That part's actually easy. Rhodey's been doing this for a long time,” he shot a look at his friend and smirked. “He's familiar with his own rut cycle, no matter how much he tries to deny it's going to happen. When he starts getting a little punchy, he comes to you. I give you your shot, and then an hour after that everyone's happy. Well, hopefully a _little_ more than an hour.” Tony leered at Jim.

Jim hyper-focused on Darcy like he was trying to pretend Tony wasn't there. “You're okay with being knotted by a stranger?”

“Sure. I mean... As long as you sign the contract.” His eyebrow rose in question. “I'm an Omega-for-hire, there's a standard contract.”

He nodded, and she could practically see things falling into place in his head. “Okay.” He turned back to Tony. “Okay. But we should probably get the contract taken care of now.” That was a good idea, from the way things sounded they might be a little too rushed to get it taken care of later.

Tony clapped his hands and rubbed them together. “Excellent.” His gaze swung towards Darcy. “And you... How would you like an all-expenses-paid vacation to New York?”

* * *

 

New York wasn't bad. She got to visit with Jane, who seemed tentatively excited about the whole thing, and Thor, who told her Heimdall had been quite impressed with her.

It was only a couple of days before Tony marched into Jane's lab, a capped syringe in one hand. “Rhodey's on his way,” he told Darcy.

“Uh...” He apparently intended on giving her the shot right that second, if the way he was advancing on her was any indication. “Can, uh... Can we do this somewhere else?”

His eyes flicked between her and Jane as though noticing the other woman for the first time. Jane had a slightly amused expression on her face, apparently she was used to Tony's idiosyncracies. “Yeah. That would probably actually be a good idea.”

Darcy braced her hands on the armrests of her swiveling office chair and pushed herself to her feet. She was a little nervous again for some reason. It wasn't like this was anything she hadn't done before, and Tony had assured her over and over again that it would work... The butterflies in her stomach, however, didn't seem to care. “I'll see you in a few days?” she told Jane.

“Yeah. Good luck.” Jane gave her a bright, excited smile.

Darcy nodded. She headed for the door of the lab. Tony threw his arm around her shoulders as they walked. He didn't seem to have a concept of personal space, though Jane had assured her that was just with people he trusted. So it was a good thing?

She found herself walking back up to the little apartment she'd been giving for the duration of her stay. Little- it was huge compared to her tiny studio apartment, but Jane, Steve, and Bucky's apartment was quite a bit larger. Then again, there were three of them.

They entered the apartment, Tony humming a little under his breath. He steered her over to the kitchen table. “Drop your pants, bend over.” He sounded a little too cheerful.

She glanced back at where he was standing behind her, syringe held up in front of him. “You're kidding.”

“I'm not. This is the quickest way to get this to work.” He gestured at the table.

Sighing, Darcy undid her jeans and slid them down around her thighs. Then again, if she was going into a heat _right now_ , she was probably going to want some more comfortable pants anyway. There were yoga pants waiting in the bedroom for her.

Fingertips brushed over her ass cheek, pushing her panties up out of the way. She jumped when he stabbed her with the needle, but it was over almost before it began. “There. Make yourself comfortable, whatever it is you Omegas do when you're about to spend the next three...?”

“Five.” She let her pants drop to the floor. It wasn't like he hadn't already seen her without them.

“Five days fucking.”

She stooped and gathered up her jeans, walking down the hall towards her bedroom. Once inside she rubbed at her ass, it still ached a little. Not like it was probably going to matter in a little bit. She got changed into some yoga pants. Apparently Tony was... Staying? The front door remained firmly closed.

When she came back down the syringe was gone and he was sitting at the kitchen table, spacing out a little. His eyes snapped to her when she came back into view. Her eyes widened a little as she looked at him. “You're... Staying?”

“At least until we know if this is going to work on not.” He paused, giving her a bit of a smirk. “Of course, a first-hand observation might be helpful...”

“Not happening.” Darcy sat down at the table as well, one of her knees bouncing with nervous energy. She didn't _feel_ any different than she had a few minutes ago. As time wore on, though, she could feel the change. She got warm, she could feel herself flushing. Interest in the man across the table turned into that deep, aching need, and she couldn't stop staring at Tony's arms where they were folded across his chest.

He looked at her, eyebrow raising a little. “It seems to be working.”

Wordlessly she nodded, afraid that if she opened her mouth she'd ask him very nicely to please fuck her. This was different, she hadn't gone into heat without an Alpha around before and it was making her kinda jumpy.

Tony got to his feet. “I'm off. I'll be just a phone call away if you need anything, or just ask JARVIS.” There was something that sounded a lot like sympathy in his voice, but she had a hard time focusing past the actual movement of his lips when he spoke.

The door opened and closed, and Darcy was acutely aware that she was alone. Her body was racing hot and cold, but there was no outlet. In both of her heats before she'd had the scent of an Alpha there to wrap herself in, to calm herself with, but now there was nothing.

It wasn't long before the door opened again, although it seemed like hours. “I thought you would wait,” came Jim's clearly irritated voice.

The harsh tone set her teeth on edge, like nails on a chalkboard, but in the next second she could smell him, his warm, comforting scent, and she breathed in deeply. Her shoulders relaxed from where they were bunched up around her ears as she slumped forward.

Tony was saying something, but the door closed again before much of it made it through to Darcy. She got to her feet, turning to see Jim making his way towards her. He'd taken off his uniform at some point, was wearing a polo shirt and jeans. His expression was serious, eyes fixed on hers. When he stepped into her, she let her head fall back, exposing her throat to him.

His hands settled in the small of her back, warm through her t-shirt. “I'm sorry I wasn't here sooner, I still had to get all my stuff together. I thought Tony would wait until I got here to give you the formula.” His nose nuzzled against her pulse point, his lips brushing against the side of her neck with his last words.

The intense jolt of pleasure that spread through her somehow both soothed and excited her. “Better now that you're here,” was almost a whimper.

“I'm not quite there yet.” His breath was hot against her skin, sending a shiver down her spine. “I wanted to leave myself enough time to get back in case it didn't work.”

“It worked.” Her breath caught on a gasp as he worked the back of her shirt up and his thumb brushed against bare skin.

“I can see that.” He nosed back behind her ear, she could hear him breathing in deeply, taking in her scent. “Tony gets so excited about science sometimes that he forgets he's dealing with actual people.” His lips fluttered against her pulse point and Darcy couldn't keep in a soft moan. “Why don't we get all this off and I make you feel good.”

She moaned again, a little conflicted. The sparks his thumb against her back was sending through her made her want to feel nothing but his skin against hers, but without knotting her she wouldn't be able to actually find release. Still, she let him pull her shirt off, then hooked her thumbs in the waist of her pants and the underwear underneath and pushed them to the floor.

Jim reached behind her, undoing her bra, and she let it fall after the rest of her clothes. When he pulled his own shirt off she couldn't help but stare, her eyes roving the breadth of his shoulders, the trail of dark hair that disappeared into the waist of his jeans.

His hands settled on her hips, guiding her gently back until she bumped against the table. She pulled herself up onto it, and Jim stepped into her again. His hands slid into the small of her back and her breasts brushed against his chest. It felt like little jolts of electricity pinging through her. She reached out to him, sliding her hands up and down over his chest.

“Lay back,” he told her softly. His hands behind her steadied her as Darcy lowered herself until she was flat on her back on the table. He smoothed one hand up along the inside of her thigh even as he bent towards her.

His lips closed over the pulse point in her throat at the same time that two fingers slid deep into her cunt. Her broken moan was a little louder this time as she felt him fill her. It was so close to what she wanted, but not quite there. She cried out when he started to draw deeply on that sensitive spot in her neck, his fingers fucking in and out of her.

She clutched at his shoulders, eyes squeezed shut. He was adding to the hot ache of need deep inside her, pleasure spiraling through her until she couldn't keep still. She was rocking up into him, her fingers scrabbling against his shoulders. When his thumb flicked over her clit she let out a yell as her orgasm pushed through her. Still it wasn't enough, just like she'd known it wouldn't be.

It seemed to be enough for Jim, though. His fingers withdrew from the molten heat of her pussy, straightening away long enough to get his pants off. In just another moment she could feel him lining himself up with her slick entrance, sliding deep inside.

He started fucking her right away, setting an almost brutal pace. His hands hooked around the tops of her thighs, keeping her legs spread wide and holding her in place. She gripped at his arms, her head rolling back and forth against the table. It was hard and deep, it was exactly what she needed.

Darcy pushed up to meet every stroke, her skin sticking a little against the wooden table top. It felt so good, the dance of his hard cock over her sensitive nerves, the promise that release was coming soon.

Not too soon. But at last his pace started to falter. He drove himself deep one final time, and she locked her legs around his hips, holding him there. His knot swelled up from the base of his cock, pushing through the slickness of her pussy until it swelled right against her cervix. It pulsed there, and at last it was enough. Heat rolled through her in waves as her pleasure finally broke.

He was breathing as hard as she was, sweat beading down his forehead when she opened her eyes to look at him. He gave her a smile. “Hold onto me.” He bent down into her, and she locked her arms around his neck so that when he straightened again he took her with him.

Jim started to walk, and every step jolted his knot against her until she was crying out again. The sharp pleasure was almost so much it almost hurt, though, and it was a bit of a relief when he eased them down onto her bed.

“Just like a normal heat,” she assured him breathlessly, now that she could think again. She'd have to tell Tony. Just... Later.

He chuckled, and his lips moved over her forehead. “I'm sure he'll be very happy to hear that.”

 

**Author's Note:**

> It is definitely a series.


End file.
